Ultrasonographic method for measuring muscle deformation

Abstract

The invention relates to a method for determining deformation values of muscles, particularly skeletal muscles. According to the method, an image sequence of ultrasonic images of the muscle is obtained during a period where the patient performs a loaded action which causes the muscle to contract. During this period, the patient is guided to exert a predetermined force on an exercise device. The actually exerted force is measured simultaneously with the ultrasonic image sequence. Deformation values are determined based on the recorded image sequence. The invention also provides an apparatus for performing the method.

1 - 23 . (canceled) 
     
     
         24 . A method for determining strain values indicative of contractility of a loaded muscle of a patient, the method comprises
 setting a reference load to be exerted via a loaded action to be performed by the patient by use of the loaded muscle,   obtaining load values exerted by the patient during a measurement period comprising an action period in which the patient performs the loaded action,   based on the reference load and at least some of the obtained load values, guiding the patient performing the loaded action to exert the reference load using the loaded muscle during the action period,   obtaining an ultrasonography image sequence of the muscle at least during the action period,   selecting an analysis location ( 302 ) in at least a part of the ultrasonography image sequence subsequent to the measurement period,   based on at least some of the ultrasonography images of the image sequence, determining the strain values ( 211 ) indicative of the contractility of the muscle based on determined displacements (Δx1(t2), Δx1(t2))) of at least one identifiable location ( 501 ) within the analysis location ( 302 ), where the displacements (Δx1(t2), Δx1(t2)) are obtained based on tracking the at least one identifiable location ( 501 ) from image to image in the image sequence.   
     
     
         25 . A method according to  claim 24 , where the analysis location ( 302 ) is a single analysis location selected in at least a part of an image of the ultrasonography image sequence. 
     
     
         26 . A method according to  claim 24 , where each of the deformation values ( 211 ) are associated with a specific zone in the analysis location  302  which comprises at least one of the different locations ( 501 ). 
     
     
         27 . A method according to  claim 24 , where the displacements are obtained based on tracking each of the different locations ( 501 ) from image to image in the image sequence. 
     
     
         28 . A method according to  claim 24 , where the different locations ( 501 ) are different unique speckle patterns. 
     
     
         29 . A method according to  claim 24 , where the image sequence is obtained at a rate greater than 100 images per second. 
     
     
         30 . A method according to  claim 24 , further comprising determining the deformation values ( 211 ) associated with a predefined deformation-direction ( 512 ,  513 ,  514 ). 
     
     
         31 . A method according to  claim 30 , comprising determining the deformation values ( 211 ) for two or more predefined deformation-directions ( 512 ,  513 ,  514 ). 
     
     
         32 . A method according to  claim 30 , where the deformation values ( 211 ) for the one or more predefined deformation-directions ( 512 ,  513 ,  514 ) are determined based on a direction ( 514 ) of displacements of at least one of the locations ( 501 ). 
     
     
         33 . A method according to  claim 24 , where setting the reference load to be exerted comprises setting the reference load to a percentage of a measured maximum load exerted via the loaded action previously performed by the patient. 
     
     
         34 . A method according to  claim 33 , further comprising
 prior to setting the reference load, obtaining peak load values exerted by the patient during a peak load action period in which the patient exerts a maximum load while performing the loaded action,   determining the measured maximum load from the obtained peak load values.   
     
     
         35 . A method according to  claim 24 , where guiding the patient comprises displaying the reference load and a history of at least some of the load values obtained during the action period. 
     
     
         36 . A method according to  claim 24 , where the muscle is a skeletal muscle. 
     
     
         37 . A method according to  claim 24 , where the loaded action is performed by exerting a load on an exercise machine capable of measuring the exerted load. 
     
     
         38 . A method according to  claim 24 , where the measurement period is initiated by a user activated trigger function. 
     
     
         39 . A method according to  claim 24 , where the method further comprises selecting an analysis location in at least a part of the ultrasonography image sequence subsequent to the measurement period, and where the determination of the deformation values is based on the selected analysis location in a plurality of the ultrasonography images in the ultrasonography image sequence. 
     
     
         40 . A method according to  claim 24 , where each of deformation values are determined on basis of at least two of the ultrasonography images in the ultrasonography image sequence, where each of the at least two ultrasonography images have been obtained at different time points during the action period. 
     
     
         41 . A method according to  claim 24 , where the method further comprises obtaining an EMG signal indicative of the myoelectric activity of the muscle at least during the action period. 
     
     
         42 . A method according to  claim 41 , where the method comprises displaying the deformation values and the EMG signal at least for the action period, where the displaying is performed subsequent to the measurement period. 
     
     
         43 . A method according to  claim 24 , where the method comprises displaying the deformation values and the force values at least for the action period, where the displaying is performed subsequent to the measurement period. 
     
     
         44 . A method according to  claim 24 , where the process of obtaining the load values and the ultrasonography image sequence are synchronized in time. 
     
     
         45 . A processing device arranged for obtaining an ultrasonography image sequence for determining strain values indicative of contractility of a loaded muscle of a patient, the device comprises
 a guiding function arranged to receive,
 a reference load to be exerted via a loaded action to be performed by the patient by use of the loaded muscle, 
 load values exerted by the patient during a measurement period comprising an action period in which the patient performs the loaded action, where the guiding function is further arranged to guide the patient performing the loaded action to exert the reference load using the loaded muscle based on the reference load and at least some of the obtained load values, and 
   an analyzing function arranged to receive the ultrasonography image sequence of the muscle, where the ultrasonography image sequence is obtained at least for the action period, and arranged to determine the strain values ( 211 ) indicative of the contractility of the muscle based on at least some of the ultrasonography images of the image sequence and based on determined displacements (Δx1(t2), Δx1(t2)) of at least one identifiable location ( 501 ) within an analysis location ( 302 ) selected in at least a part of an image of the ultrasonography image sequence, where the displacements (Δx1(t2), Δx1(t2)) are obtained based on tracking the at least one identifiable location ( 501 ) from image to image in the image sequence.   
     
     
         46 . An ultrasonic video recording and processing system arranged for obtaining an ultrasonography image sequence for determining deformation values indicative of contractility of a loaded muscle of a patient, the system comprises
 the ultrasonic image processing device according to  claim 45 , and   an ultrasound scanner arranged for obtaining the ultrasonography image sequence.